Air seed meter

ABSTRACT

An air seed meter for an agricultural planter includes a vacuum cover which has a central opening which exposes the central portion of the seed disc to the exterior. The central opening of the vacuum cover is centered on a location offset from the axis of rotation of the seed disc. This reduces disc wear at the disc-vacuum cover interface, and renders the disc more accessible for self-cleaning, visual inspection and verification of the proper disc. Openings in the central, open portion of the disc, the back wall of the seed housing and the side wall of the seed housing cooperate to equalize the air pressure in the seed reservoir to atmospheric pressure and reduce or eliminate reverse air currents in the discharge chute. An adjustable brush with three separate stations cooperates with an edge-release, beveled disc to apply a progressively more forceful singulation force to eliminate duplicate seeds.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/553,349 filed on Dec. 29, 2003 for “AIR SEED METER”.

FIELD OF THE INVENTION

The present invention relates to improvements in air seed meters of thetype used to meter and “singulate” seeds in row units for agriculturalplanters. Air seed meters which use atomospheric pressure on the seedreservoir side of a rotating disc and a pressure below atmosphericpressure on the “vacuum” side (the pressure differential maintainingseeds on a rotating disc from a seed reservoir to a discharge location),are frequently referred to as “vacuum” meters, to distinguish them fromseed meters which use a differential pressure generated by atmosphericpressure and a pressure greater than atmospheric pressure to retain theseeds on the disc (“positive pressure” meters).

The principles of the present invention relate to air seed meters ingeneral, whether the pressure differential securing the individual seedsto a disc is created by a sub-atmospheric pressure on the vacuum side ofthe disc, or whether a positive pressure (above atmospheric pressure) isgenerated in the seed reservoir to secure the seeds to the disc.However, subsequent discussion and description will relate to the“vacuum” type of meter. Persons skilled in the art will readily be ableto adapt or apply the structure and operation disclosed to the positivepressure type of meter. As used herein, the word “singulate” refers toseparating one seed from a group or large number of seeds, typicallystored in a reservoir. Singulation is typically used for more expensiveseeds, to conserve costs, and to achieve the desired plant spacing forachieving maximum yield potential.

BACKGROUND OF THE INVENTION

Air seed meters have been known in the art for some time. One currentcommercial air seed meter uses an enclosure for the disc having a firsthousing section forming a reservoir for the seeds and receiving andenclosing the seed side of the disc, and a second housing section,connected to the first housing section for contacting and enclosing thevacuum side of the disc. The second housing section forms a vacuumchamber, in the case of an air meter employing suction to secure theseeds to the disc.

In most cases, two housing sections form the overall meter casing, arein the form of flat, circular end walls (i.e. disc-shaped) withgenerally cylindrical side walls. The housing sections or halves aremounted with the centers of the end plates concentric with the axis ofrotation of the disc. Moreover, in prior art meters, for the most part,a seal is formed between the vacuum cover and the seed disc.

The seed disc is driven typically for rotation about a generallyhorizontal axis. As the disc, having spaced seed apertures locatedcircumferentially about the disc, is rotated through the seed reservoir,seeds are picked up and attached to an aperture by means of a pressuredifferential between the seed reservoir and the vacuum chamber. Theseeds are held to the disc by the pressure difference as they passthrough the seed reservoir. The seed is passed to a discharge areawhich, typically, is located adjacent a downwardly facing chute formedas a tangential channel in the meter housing.

In prior art air seed meters which seek to establish a seal between thevacuum housing and the rotating disc, the seal extends around theperiphery of the portion of the vacuum housing which forms the actualvacuum chamber. That is, a portion of the vacuum chamber typically isdevoted, in prior art devices, to a point for releasing the seedssequentially into the discharge chute. This is done, in some cases, byhaving the seeds pass into a region adjacent the discharge chute. The“vacuum” (i.e. lower pressure) side of the disc, as it passes adjacentthe discharge chute, naturally is exposed to air pressure near, but notalways at atmospheric levels.

There are some difficulties associated with such arrangements. First, itis desirable to establish atmospheric pressure at the actual point ofdischarge. For example, the higher the air pressure differential acrossthe seed disc at the moment of discharge, the less would be the tendencyto release the seed at the same location accurately. Any variation inthe pressure differential across the seed disc at the intended point ofrelease, will create variances in the spacing of the seeds upondischarge and deposit into the seed furrow. According to thesestructures, it became necessary, in some cases, to create an elaboratesealing mechanism which defined only the boundary of the vacuum chamberand excluded the region of release adjacent the discharge chute.

Still further problems existed in that a “chimney effect” may be createdin the discharge chutes of some existing meters. By this it is meantthat as seed is routed to the release point in the discharge chute, itwill be appreciated that the reservoir side of the seed disc is atapproximately atmospheric pressure; and if measures are not taken, theinterior of the seed reservoir may be at a slightly sub-atmosphericpressure. This also increases the likelihood that air is drawn up thedischarge chute (i.e. if the reservoir is at a pressure even slightlybelow atmospheric), resulting in a “chimney effect” or updraft of air inthe discharge chute and requiring compensation. The chimney effect notonly reduces the reliability of accurate seed release, and thereforespacing, but depending upon the velocity of air flowing in a reversedirection in the seed discharge chute, it might alter the dischargeflight path of the seed, thereby further affecting the fall time (andultimate spacing) of seeds.

Some prior art seed discs which use recesses or “cells” in the surfaceof the disc to capture and seat seeds experience another source ofpossible inconsistent or unequal seed spacing upon delivery to thefurrow. Specifically where the seed is required to move axially of thedisc (i.e. parallel to the axis of rotation) to release, there is anincreased tendency for the seed to strike the wall of the dischargechute and to ricochet off the walls of the chute and to be delayed inrelease from the cell. This effect creates variation in the length ofseed travel (and thus variations in delivery time) from release todeposit, and thus results in inconsistency in seed spacing in thefurrow.

Other seed discs, which do not have recesses or depressions in the seeddisc for retaining seeds, require the use an auxiliary device, someshaped like a spider with wire legs, to agitate and bring the seeds inthe reservoir up to the speed of the disc to facilitate seating of theseeds on the disc.

Another difficulty with such prior art air meters as described above, isthat for the most part, the seal between the disc and the vacuum housingis generally a circular path centered on the axis of rotation of thedisc and located at the perimeter of the disc. In such structures, theportion of the disc engaging the circular seal tends to create a narrowannular region of engagement between the seal member and the disc orseal, thus creating a narrow band of wear on the disc. This wear “ring”creating wear on the disc or seal, results in a variance between thesurface of the disc which was attempted to be sealed and the contactsurface of the seal, thus reducing the effectiveness of some seals.

Moreover, such prior art structures rendered it difficult to clear theinterior of the vacuum chamber as well as the exterior from fineparticles, dust, dirt and chips or broken segments of seeds that mayhave cracked (collectively referred to as “debris” or “fines”). Suchparticles could pass through or obstruct the apertures in a seed recessand may even accumulate between contacting surfaces where it wasdifficult, due to the nature of some prior devices, to clear the debris.Some prior art devices, such as disclosed in U.S. Pat. No. 6,247,418,created tiny slots between a seal of the vacuum housing and the disc sothat air could flow across the seal through the groove in the adjacentsurface of the disc between the contact surfaces to clear the disc andseal surface of fine particles. However, the cross section of such slotstended to reduce, with diminished clearing effect, as the sealing memberwore into the surface of the disc, thereby reducing the dimensions inand effectiveness of the clearing passageways.

SUMMARY OF THE PRESENT INVENTION

The present invention includes a vacuum cover which has a semi-toroidalshape, but which is not a completely closed shape. By this, it is meantthat the vacuum chamber extends partially but not completely about theperiphery of the main seed housing of the meter, (thus making the vacuumhousing “segmented” in the sense that it does not extend completelyabout the circumference of the seed reservoir housing). Moreover, thevacuum cover of the present invention does not have a flat, disc-shapedouter wall and a generally cylindrical side wall so as to match, ingeneral, the housing for the seed reservoir. Rather, in radial crosssection, the vacuum housing of the present invention has a generalU-shape, forming an enclosure extending partially about the periphery ofthe disc and having spaced, opposing end walls.

The shape of the vacuum housing provides a closed wall having twoperimeters for engaging the remainder of the meter. The outer perimeterof the vacuum housing, which is generally circular, is located outwardlyof the seed openings in the disc and that conforms in general to theouter perimeter of the seed housing and provides a flange for mountingto the seed meter housing and partially enclosing the disc. The inneredge of the vacuum cover lies inwardly of the seed openings in the disc,and is also curved to define a central opening which is generallycircular. The center of this central opening in the vacuum cover,however, is not concentric with the center of the disc, which definesthe axis of rotation of the disc. The central opening of the vacuumcover is smaller in diameter than the disc; and the center of thecentral opening is off-set or eccentric relative to the axis of rotationof the disc which is at the center of the disc. This arrangement has theadvantage that the region of engagement between the disc and the vacuumcover defined by the contact area between the two is not a narrow,annular or circular region on the disc. Rather, as the disc rotates, thecircular contact area between the inner edge of the vacuum cover and thedisc moves progressively in a non-concentric manner about the disc, thusdistributing or spreading out the total area of contact between the two,and reducing the wear per unit area of contact.

The inner curved contact surface of the vacuum cover is provided withseveral spaced segments, each including a series of circumferentialgrooves (that is, they are spaced in alternate fashion with contactsurfaces from the center toward the periphery). In the illustratedembodiment, each sealing segment has three such grooves which formcurved areas which do not engage the disc. This design further reducesthe surface contact between the disc and the associated portion of thevacuum meter housing and enhances the sealing function of each sealingsegment while reducing wear on the disc.

Moreover, generally radial slots are provided between adjacent sealingsegments of the inside edge of the vacuum cover. These slots separatethe grooved sealing segments and extend generally radially of thecentral opening of the vacuum cover, but they are slightly inclinedrelative to a radius. Specifically, the slots extend outwardly andslightly incline in the direction of rotation of the disc whenproceeding from an inner location to an outer location. Further, theslots are enlarged in cross sectional area proceeding from inner toouter locations. Thus, the slots are less likely to become clogged withfines; and the fines are delivered in a direction facilitating theirbeing entrained in the air flow into the vacuum chamber from which theyare evacuated. This permits the innermost central opening of eachclearing slot to clear the central open area of the disc by permittingfines to be drawn into the vacuum chamber and evacuated. It alsoprevents the fines from getting caught between contacting adjacentsurfaces of the disc and vacuum cover.

It will thus be appreciated that the combination of spaced, groovedsealing segments on the inner contact edge of the vacuum cover, togetherwith the inclined, radial slots separating the sealing segments do notform a complete seal between the cover and the disc. Rather, what isformed is what is referred to as an “air dam” or controlled air barrierbetween the external atmosphere and the interior of the vacuum chamber,permitting a continuous, controlled flow of air from the atmosphere intothe interior of the vacuum chamber for purging the contact regionbetween the disc and inner edge of the vacuum cover of debris andclearing the central, exposed portion of the disc adjacent thedisc/vacuum cover contact. This arrangement also aids in controllingundesired leakage of air, and it extends the useful life of the disc.

Another area in which the present invention improves on prior designs ofair seed meter is in establishing a more uniform pressure differentialbetween the two surfaces of the seed disc by establishing a uniformityof atmospheric pressure throughout the seed reservoir. This isaccomplished by designing air inflow to the seed reservoir to compensateto air lost to the vacuum. In one aspect, a slotted insert is providedto overlay a large aperture on the back wall of the seed housing. Theslots are sized such that they contain the seeds in the reservoir, butthey are extended in length to permit air to flow inwardly over anextended region. Secondly, an opening is formed in the side wall of theseed housing adjacent the entrance of the discharge chute to reduce any“chimney” effect described above. In addition, if desired, the disc maybe provided with additional apertures located in the central portion ofthe disc, which is located in the central opening of the vacuum coverwhen the disc and vacuum cover are assembled. In combination, thesefeatures permit make-up atmospheric air to flow into the reservoir overa distributed area to equalize atmospheric pressure within the seedreservoir over a wide range of operating conditions.

Another area of improvement in the present invention is in thesingulation of seeds. This is accomplished by locating the seed cellsextending to the periphery of the disc so the seeds do not have to moveaxially of the disc when released to clear the cell, and by providing,for each seed cell, a seed aperture or orifice extending through thedisc for communicating the vacuum source with the reservoir for securingthe seed. In addition, adjacent each seed orifice (in the corn disc)communicates with a pair of seed recesses in the reservoir side of thedisc including a circumferential recess extending in the direction ofrotation, and a radial recess extending radially inward toward thecenter of the disc. The circumferential recess facilitates seating of aseed and guidance of the seed into communication with the seed orificeand then securing the seed once seated and singulated. The radial recessextends from the seed orifice toward the center of the disc and itpromotes removal of duplicate seeds, in combination with the singulatormechanism.

The singulator mechanism of the present invention comprises a series ofthree brushes extending radially inwardly of the disc and inclinedslightly in the direction of rotation of the disc when proceedinginwardly of the periphery of the disc. Each brush comprises two sets ofbristles and tends to dislodge a duplicate seed if it is present andcompeting for a seat. It has been found that the inclusion of threeseparate, spaced brushes enhances the accuracy of the meter by rejectingduplicates, usually at the first two brush stations, yet permitting eachorifice to be filled with a seed.

The brushes of the singulator are mounted in a single body which isadjustable radially of the seed disc by means of a lever accessible,externally of the meter. The brushes are arranged for progressively moreaggressive singulating action. The adjustment lever is easily accessibleand quickly, conveniently and accurately manipulated. The outer edge ofthe seed disc is beveled so that the singulating brushes may extend moreeasily inwardly of the disc to engage and dislodge duplicate seeds fromthe seed cells, and to facilitate radial movement of the seeds as theyare released.

Other features and advantages of the present invention will be apparentto persons skilled in the art from the following detailed description ofthe illustrated embodiment wherein identical reference numerals willrefer to like parts in the various views.

BRIEF DESCRIPTION OF THE DRAWINGS

As used herein, “right” and “left” refer respectively to the left andright side of a planter row unit or meter from the viewpoint of anobserver standing to the rear of the planter and facing in the directionof travel. Further, “front” refers to the direction the observerfaces—i.e. the direction of forward travel of the planter. Thesereferences are optional and solely for convenience of description.

FIG. 1 is a perspective view of a planter row unit incorporating thepresent invention taken from the upper, rear and left side of the unit;

FIG. 2 is a left side elevational view of the row unit of FIG. 1;

FIG. 3 is an upper, frontal and left side perspective view of an airseed meter incorporating the present invention;

FIG. 3A is a lower, rear left side perspective view of the seed meter ofFIG. 3;

FIG. 4 is a perspective view taken from the upper, rear and left side ofthe meter of FIG. 3 with some components shown in exploded relation;

FIG. 4A is a fragmentary close-up perspective view of the seedsingulator of the meter, with the components in exploded relation;

FIG. 5 is a perspective view of the meter of FIG. 3 taken from the frontand left side, again with some components in exploded relation;

FIG. 5A is a lower perspective view of the singulator with components inexploded relation;

FIG. 6 is a lower, left side perspective view of the vacuum cover;

FIG. 7 is an interior elevational view of the vacuum cover of FIG. 6;

FIG. 8 is a lower, rear interior perspective view of the vacuum cover ofFIG. 6;

FIG. 9 is an upper, rear perspective view of the interior of the housingof the meter of FIG. 3;

FIG. 10 is a view similar to FIG. 9 with the brush separator insertassembly in exploded relation;

FIG. 11 is a perspective view of an alternate seed disc of the meter ofFIG. 3, showing the reservoir side of the disc;

FIG. 12 is an enlarged, fragmentary elevational view of a section of theperiphery of one seed disc of FIG. 3A showing the seed cells;

FIG. 13 is an enlarged, transverse cross-sectional view of a peripheralsegment of a seed disc taken through the sight line 13-13 of FIG. 12.

FIG. 14 is an enlarged, fragmentary, perspective view of the peripheryof the seed disc of FIG. 12 showing seeds seated in adjacent seed cells;

FIG. 15 is a side view of a portion of a seed disc and the singulatormechanism in operative relation;

FIG. 16 is a view similar to FIG. 15, with the singulator adjusted to alocation further from the seed retention opening;

FIG. 17 is a side view of the vacuum cover and seed disc with a portionof the structure sectioned along the sight line 17-17 of FIG. 17A;

FIG. 17A is a side elevational view of the reservoir side of the seeddisc and vacuum cover in assembled relation;

FIG. 18 is an elevational side view of a portion of the seed disc ofFIG. 3 adjacent the release point of the seeds and showing the seeddischarge for an idealized release;

FIG. 19 is a left side elevational view of the air seed meter of FIG. 1;

FIG. 20 is a cross section view taken through sight line 20-20 of FIG.19; and

FIG. 21 is an enlarged view of the portion of FIG. 20 enclosed withinthe chain line loop of FIG. 20.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Referring first to FIG. 1, reference numeral 10 generally designates aplanter row unit incorporating the air seed meter of the presentinvention. Briefly, the row unit 10, aside from of the inventive airseed meter is known in its general aspects to persons skilled in theart. The row unit includes a U-bolt mount generally designated 11 formounting the row unit to a conventional planter frame or tool bar, as itis sometimes called, which may be a steel tube of 5 by 7 inches(although other sizes are used, as well).

The mount 11 includes a faceplate generally designated 12 which is usedto mount left and right side parallel linkages, each linkage being afour-bar linkage such as the left one seen in FIG. 1 and generallyidentified by reference numeral 14. The double linkage is sometimesdescribed as having upper parallel links and lower parallel links, andthe rear ends of all four parallel links are pivotally mounted to theframe of the row unit generally designated 15. The frame 15 includes asupport for a seed hopper 16, as well as a structure including a shankweldment generally designated 17 for mounting a pair of ground-engaginggauge wheels, one of which is shown at 18, as well as a furrow closingunit generally designated 19 which includes a pair of inclined closingwheels. The row unit also includes a pair of furrow opener discsdesignated 26 in FIG. 2.

As is well known in the art, seed is placed in the hopper 16 and fed toa meter, a portion of which is seen at 20 in FIG. 1. The meter 20singulates and deposits seed as the row unit is pulled along, into afurrow prepared by a conventional disc opener 26 placed between andextending in front of the gauge wheels 18. The furrow is then closed,after the seed is deposited, by the closing wheels 19.

Turning now to FIGS. 3 and 3A, there is shown, in perspective view, aseed meter 20 constructed according to the present invention. The seedmeter 20 includes a housing 21 which receives seed from the hopper 16and forms a seed reservoir, and a removable vacuum cover generallydesignated 22.

Referring to FIGS. 4 and 5, the major components of the seed meter 20are shown in exploded relation. To the lower left of FIG. 4 is thevacuum cover 22 which is located on the outer or left side of the meter.A seed disc 23 is driven by a hub 25. Hub 25 engages the disc 23 anddrives it in rotation (counter clockwise as seen in FIG. 4) about ahorizontal axis identified by reference numeral 28. The hub 25 ismounted to a shaft 29 which is fitted with a bearing 31. The shaft 29 isprovided with a pair of bores 33, 34 which receive pins 35, 36respectively. Pin 35 mounts the hub 25 to the shaft 29 by means of acollar 38, which is also provided with a pair of apertures one beingdesignated 39 in FIG. 4. The apertures 39 of the collar 38 are alignedwith the aperture 33 of the shaft 29 to receive the pin 35. The aperture34 and pin 36 of the shaft 29 are used to mount the shaft 29 to a drivecoupling on the planter. The drive shaft is designated 40 in FIG. 2.

Referring now to the hub 25, it includes a plate 41 which includes threelobes, each having a tapered drive lug 42. The tapered drive lugs 42 arereceived in elongated apertures 44 of the disc 23 (see FIG. 3). Theapertures 44 are spaced equally from a central opening 45 of the disc 23which receives the collar 38 of the hub 25. The taper of the lugs 42 issuch that they are wider toward the base (i.e. plate 41) so that thelugs engage and enter the openings 44 of the disc 23 and urge the disctoward the vacuum cover 22 when the meter is assembled. In this manner,the disc 23 is closely adjacent and urged toward an inner flange of thecover 22, to be described, so that there is contact between the two.When the vacuum is applied, the disc 23 is drawn into more intimatecontact with the cover 22 to maintain a sub-atmospheric pressure(“vacuum”) within the cover 22, as will be further described within. Thedrive coupling connects to the shaft 29 from the outer side of themeter, as seen in FIG. 3 by the operator or maintenance personnel andconnecting the planter drive to the meter.

It will be observed from FIGS. 3 and 4 that each of the drive lugs 42 iselongated laterally and inclined relative to a radial line extendingfrom the axis of rotation 28. In the illustrated embodiment when viewedfrom the left (outer) side of the meter and as seen in FIG. 4, therotation of the disc is counter-clockwise. The inclination of the drivelugs 42 relative to a radial line or plane is that the direction ofelongation of the lugs extends closer to the axis of rotation whenmoving in the angular direction of rotation. The receiving apertures 44of the disc 23 are similarly oriented and have the same cross-sectionalshape. This arrangement insures that the disc cannot be mounted indriving relation with the hub 25 if the surfaces of the disc 23 arereversed. In other words, the vacuum surface of the disc (the surface23B seen in FIG. 4) must face outwardly and the reservoir side of thedisc 23A in FIG. 5) must face inwardly of the meter in order for properdriving engagement between the hub and disc to be established. Thisprevents improper assembly of discs in the meter. Moreover, the drivelugs 42 are tapered in an axial direction, being reduced incross-section proceeding axially toward the disc.

Referring to FIGS. 4, 9 and 10, the meter housing 21 includes an uprightback wall 46 which is circular and disc-like, and a cylindrical sidewall 47 which extends toward the vacuum cover 22 and receives the coverfor mounting by means of four mounting lugs 48 received in bosses 48Aformed on side wall 47, and described further within. The back wall 46includes a first opening 51 through which seed is admitted from thehopper for forming a reservoir of seed within the housing 21, bounded onthe left (outer) side by the non-vacuum (or “reservoir”) side 23A ofdisc 23.

Referring to FIGS. 4, 5, 9 and 10, an optional, adjustable plate 152 maybe included to form a gate to adjust the seed inlet opening 51 from seedchute 69 to the seed reservoir. The plate 152 includes two parallelslots 156 which receive bosses 159, which guide the plate 152 inadjusting the seed inlet opening 51. A third slot 157 extends parallelto slots 156 and receives a thumb screw 150 which is threaded into therear wall 46 of the meter housing to secure the plate 152 to thedesired, adjusted position.

The rear wall 46 also includes an integrally mounted central boss orjournal 53 into which the bearing 31 of the shaft 29 is pressed formounting the drive hub 25. A second, larger opening 55 is formed in theback wall 46 of the housing. A plastic member referred to as an“insert”, in the general form of a half disc, and generally designated58 in FIG. 4, is located to cover the opening 55 in the back wall 46.The insert 58 is sized to be received within the housing 21; and theinsert 58 is provided with a series of elongated, narrow, spaced slotsgenerally designated 60 (FIG. 9) which extend laterally across theopening 55 in the rear wall of the meter housing 21. When the insert 58is assembled to the housing 21 (by means of male and female connectors62, 63 in FIG. 10), the slots 60 extend across the opening 55 and permitair to enter into the housing 21 so as to provide a uniform distributionof air at atmospheric pressure within the seed reservoir. Referringparticularly to FIG. 9, the insert 58 is shown in its mounted position.The width of the slots 60 is small enough to prevent seeds from passingthrough. Different inserts, with different slot widths may be used forseeds of different size. The slots, together with air inlet apertures 52in the disc 23 and an opening 54 extending partly in the side wall 47and rear wall 46 of the housing 21, cooperate to establish uniform airpressure at atmospheric level substantially throughout the entire seedreservoir and the interior of the housing 21, including the point ofseed release.

A seed singulator device 61, discussed further within, is mounted to theexterior of the side wall 47 near the top of the housing 21. The lower,forward portion of the side wall 47 of the housing 21 is formed todefine three sides of a seed discharge spout 65. A discharge cover, seenat 66 in the lower left hand portion of FIG. 4 and assembled in FIG. 9,is secured to the discharge spout 65 to enclose the discharge area.Clips 67 of cover plate 66 are received in latches 68 formed in thehousing 21 adjacent the discharge spout 65. A conventional seed tube(not seen in the drawing) is mounted below the discharge spout 65 forreceiving and delivering seed to the open furrow, as is known in theart.

An inlet seed chute 69 is formed integrally with rear wall 46 andincludes a mounting flange 70 for mounting the meter to the bottom ofthe seed hopper 16. Chute 69 funnels seed from the bottom of the hopperthrough seed inlet opening 51, sized by the adjustable gate 152 into theseed reservoir formed by the housing 21 and the seed disc 23. Insert 58includes an integral bristle brush 72). The brush 72 forms a lateralwall defining the seed reservoir to prevent seeds from spilling directlyinto the discharge chute 65.

Turning now to FIGS. 3, 3A and 6-8, the vacuum cover 22 includes anouter shell or wall designated 73 has a generally toroidal form which istruncated or incomplete in the sense that the shell 73 extendscircumferentially from a first end wall 74 to a second, opposing endwall 75. The opposing end walls 74, 75 are spaced to define an opensector generally designated 78 in FIG. 7 in which the vacuum cover doesnot extend, except for an axially extending continuation wall 83, to bedescribed. Because the disc rotates counter clockwise in FIGS. 3 and 3A,the end wall 74 may be thought of as a beginning or starting wall, andthe wall 75 may be termed a final or terminating end wall.

The shell 73 includes an upper wall 80, an outer side wall 81 and aninner side wall 82 which, together with end walls 74, 75, form anenclosure, except for vacuum coupling 92. Inner side wall 82 of thevacuum cover has a generally cylindrical form which continues betweenthe starting end wall 74 and the terminating wall 75, forming thecontinuation section 83 which adds strength to the vacuum cover. Wallsection 83 defines a raised portion or bridge 84 which permits debris tobe discarded, as will be described. The corners of the shell 73 of thevacuum chamber may be beveled, as seen in the drawing, or curved orsquared. Thus, the vacuum chamber 85A (FIG. 7) is in the form of aclosed tunnel having a general C-shape or crescent shape when viewedfrom the left, extending from start wall 74 to the terminating end wall75, and enclosed by the shell 73 which has a generally inverted U-shapein cross section (FIG. 20), with the distal ends of the legs of the “U”adjacent the disc 23. The outer and inner sidewalls 81, 82 of the vacuumcover may be generally cylindrical or frustoconical. However, theirrespective inner disc-engaging edges are circular with the centersspaced from one another. Thus, the cross-sectional area of the vacuumcover taken in a radial plane (relative to the center of the opening 85)increases progressively from the start wall 74 and the end wall 75 tothe vacuum coupling 92. This has the effect of balancing or equalizingthe pressure within the vacuum chamber at different circumferentiallocations about the circular arrangement of seed cells.

The inner or central portion of the vacuum cover 22 is open—this areabeing designated 85 in FIGS. 6, 7 and 8. Thus, referring to FIGS. 3 and3A, the adjacent or “vacuum” side of the disc 23 is open to the exteriormay be seen and accessed through the opening 85 from the left or outerside of the meter. This is considered advantageous for a number ofreasons. First, the center of the vacuum side 23B of the disc is readilyavailable for visual inspection for wear or damage or for cleaning. Thedisc may be color-coded for different seeds, and the color is readilyaccessible by the farmer. Moreover, as will be discussed, the air flowinto the vacuum chamber is able to be controlled and augmented so thatthere is a continuous flow of air through the vacuum chamber to evacuatefines and seed remnants, not only from within the vacuum chamber, butfrom the exposed portion of the disc 23 adjacent and within opening 85formed by the inner wall 82 of the vacuum cover 22. Further, for discsof certain seeds, it may be desirable to include air inlet aperturessuch as those seen at 52 in FIGS. 3 and 4 in the central portion of theseed disc to 23 admit air into the seed housing 21 to augment air beingintroduced through the slots 60 of the insert and through opening 54 inthe rear wall of housing 21, all of which cooperate to equalize theinterior pressure of the seed reservoir to atmospheric pressure.

Referring primarily to FIG. 6, it will be recalled that the disc 23rotates in a counter-clockwise direction relative to the vacuum cover 22when viewed from the exterior. A seed cell or aperture enters the vacuumchamber beneath the start end wall 74 of the cover 22 and rotatescounter-clockwise. The vacuum promotes seed placement in a seed cell (tobe described), and the disc continues to rotate past the second orterminating end wall 75 where the disc then exits the vacuum chamber(see seed orifice 79 in FIG. 3A) and re-enters the atmosphere in theopen or uncovered sector 78 between the opposing walls 74, 75. It willbe appreciated that when a seed orifice, such as the one designated 79in FIG. 3A passes beneath the terminating end wall 75 of the vacuumchamber, atmospheric pressure is immediately applied to the vacuum sideof a seed cell, i.e. across the disc, and the seed is released into thedischarge spout 65 with a reliable and repeatable action, thus improvingthe accuracy of seed spacing.

Returning to FIG. 6, it will be observed that the start end wall 74 ofthe vacuum chamber, is provided with an inclined section designated 77,the lower edge of which engages the vacuum side of the disc (whichrotates counterclockwise as seen in FIG. 6). The inclined wall section77 acts as a scraper to remove debris from the portion of the discpassing into the vacuum chamber, and directs that debris downwardlythrough the open sector 78 of the vacuum cover 22, where the debrisfalls from the meter unobstructed

An inner, lower edge of the inner side wall 82 of the vacuum cover 22 isprovided with a formed, beveled surface 87 which tapers inwardly towardthe disc 23 and toward the center of the central opening 85 of thevacuum cover 23. This beveled surface 87 provides an inclined,circumferentially curved surface to clear and clean the adjacent outersurface of the disc (which is the vacuum side) of any foreign matter byscraping. Materials which are thus loosened and removed from the vacuumside 23B of the disc 23 also fall freely downwardly through the raisedportion 84 of the continuation wall 83 of the cover through the opensector 78 of the housing 21.

A peripheral mounting flange 90 is formed at the base of the outer sidewall 81 of the vacuum cover 22. The outer flange 90 is not continuousabout the vacuum cover in order to leave the open sector 78 free ofobstruction. The mounting flange 90 defines a series of keyhole slotssuch as those designated 91 for fitting over and coupling withassociated mounting studs or lugs 48 (FIG. 5) secured in bosses 48Aformed on the sidewall 47 of the housing 21. The studs 48 have enlargedheads (see 50 in FIG. 3A). To assemble the cover 22 to the housing 21,the flange 90 of the cover is placed against the edge 49 of the housing,with the studs 48 aligned with associated slots 91, and with the heads50 received in the larger aperture of an associated keyhole slot 91. Thecover is then rotated counterclockwise (in the direction of discrotation) until the base of the studs enter the narrow portion of thekeyhole slot (see FIG. 6), thereby locking the cover to the housing. Amanual clockwise rotation of the cover unlocks it from the housing andpermits removal of the cover without the need for power assist or anytools whatever.

The upper, central portion of the top wall 80 of the cover 22 is formedinto a coupling 92 to receive a hose or conduit connected between thevacuum cover 22 and the source of suction, which typically is a fandriven by a hydraulic motor, in the case of a planter.

Referring now to FIGS. 7 and 8, the under or marginal surface 95 of thebeveled flange 87 of the inner wall 82 of the vacuum cover 22 is a flatsurface which engages the adjacent surface of the disc 23 and remains incontact with that surface in a manner such that the radial inner edge 94of the beveled flange 87 brushes or scrapes away debris from the part ofthe vacuum surface of the disc 23 which it engages. The center of thecentral opening 85 of the cover 22 is offset from the center or axis ofrotation of the disc. In the illustrated embodiment, the center of thecentral opening 85 is below the axis of rotation of the disc 23. By thisarrangement, the inner marginal or contact surface 95 of the cover whichcontacts the disc does not form a narrow contact band and correspondingnarrow wear pattern as would occur if the center of the central opening85 of the vacuum cover 22 were located on or near the axis of rotationof the disc. Rather, due to the eccentric location of the opening 85relative to the axis of rotation of the disc, the wear pattern broadensout beyond the thickness of the contact surface 95 adjacent the innerbeveled edge 94 as the disc rotates, thus broadening the contact regionand reducing the wear on any one given region of the disc which contactsthe inner marginal surface of the cover.

The marginal surface 95 the beveled flange 87 can be seen to becomprised of a series of segments separated by radial slots 107. Themarginal surface 95 is divided into five sectors or sections in theillustrated embodiment, designated respectively 100, 101, 102, 103 and104 in FIG. 7. Each segment 100-104 has a set of three circumferentialgrooves 96, 97, 98; and the sectors are divided by a series of radiallyoutwardly extending slots designated 107. The radial slots 107 have, asseen in FIG. 7, an increasing width (and cross sectional area)proceeding away from the center of the central opening 85. The axis ofeach slot 107 is inclined slightly away from a direct radial line andtoward the direction of rotation of the disc (clockwise in FIG. 7). Thispromotes the flow of debris into the vacuum chamber.

The purpose of the arrangement of radial slots 107 and sealing segments100-104 is to create an air dam or barrier between the cover and thedisc so that air from the central opening 85 flows between theindividual segments 100, 101, 102, 103 and 104 of the air dam, throughslots 107 in a controlled and continuous manner, suctioning into thevacuum chamber, as the disc rotates, any fines or other debris capableof passing through the slots 107 and into the vacuum chamber 85A wherethese materials are then evacuated by passing through coupling 92 andultimately expelled by the vacuum fan.

The inner surface of the vacuum housing is made rough or textured byconventional means, so as to reduce any tendency to have seed treatmentsor powder adhere to it. Discs of different thickness may be used withoutmodification of the rest of the structure, as will be described.

Turning now to FIGS. 11-16, the seed disc 23 is seen to comprise aseries of circumferentially located seed cells, generally designated110. The seed cells 110 are, in the illustrated embodiment, spaced aboutand immediately adjacent to the periphery of the seed disc 23. As willbe further described within, it is considered an important feature ofthe present invention that the seeds are delivered, at the point ofrelease, directly tangentially outwardly of the disc, rather than havingan axial (that is, downward and to the left in FIG. 11) component ofmotion. As explained above, such an axial component of motion is likelyto lead to ricocheting of the seeds off the walls of the dischargechute, thereby adding uncertainty as to the flight time of the seed fromthe point of release to the location of lodging in the base of theformed furrow, and rendering the spacing of seeds non-uniform.

As seen in FIG. 11, the disc 23 (which may be used for peanuts, forexample) rotates in the direction of the arrow 115, hence, the side ofthe disc 23 seen in FIG. 11 is the reservoir side 23A of the disc 23,whereas the vacuum side of the disc is seen, for example, in FIG. 3A.The outer edge of the disc may be tapered or beveled, as seen best at116 in FIG. 13.

Referring particularly now to FIGS. 12 and 13, There is shown a discwhich may be used for corn seed. Each of the seed cells 110 includes acircumferential recess 111 and a radial recess 112 in communication witha seed orifice 113 which communicates the vacuum to a seed seated in acell. The circumferential recess 111 is thus extended or directed in thedirection of rotation. In other words, if a seed is located adjacent theouter perimeter of the disc 23, it will first encounter thecircumferential recess 111. The function of the circumferential recess111, which deepens or is progressively recessed from the leading edge111A toward the seed orifice 113, is to promote the travel of a seedtoward the lower portion of the seed cell and the adjacent opening ofthe seed orifice 113. As seen in FIG. 12, the seed orifice 113 extendsfrom the base of the seed cell down to the vacuum side of the disc,designated 23B in FIG. 13. The lower portion of the seed orifice 113 ischamfered as at 117.

As best seen in FIG. 12, the outermost, peripheral portion of thecircumferential seed recess 111, designated 111B, is open and leads intothe chamfer 116. Thus, when a seed is released from the cell, it is freeto move tangentially outwardly immediately (as can be appreciated fromFIG. 13), unobstructed by any portion of the disc, under bothcentrifugal force and gravity, because the seed is released at alocation of approximately 8:00 o'clock when viewing the vacuum chamber,and considering the location of the terminating end wall 75 of thevacuum cover.

The radial recess 112 of each seed cell facilitates the dislodgement orseparation of duplicate seeds—that is, the purpose of each seed cell isto allow the singulator to isolate and secure (i.e. “singulate”) asingle seed in each cell.

Referring now to FIG. 14, a close up view of adjacent seed cells isseen, individual seeds designated S are received in, and secured bymeans of the vacuum to the disc via the seed orifice 113.

Turning now to FIGS. 4, 5, 15 and 16, the singulator device 61 will bedescribed. The singulator includes a holder 119 which may be of asynthetic or plastic material. Three sets of brush bristles designated120, 121 and 122 are carried by and secured to the holder 119. Each setof bristles comprises a brush, and they all may be similar, so that onlyone need be described. The brush 120, which is the leading brush setincludes first and second sets of bristles or “tufts” 123, 124 (FIG. 5A)which extend or are inclined downstream in the direction of rotation 115relative to a radial line.

Turning now to FIGS. 4A and 5A in particular, the rear of the brushholder 119 is provided with a generally cylindrical extension 125 whichdefined a radial opening 125A which receives a spring 126. The extension125 is received on and secured to a bracket 127 fixed to the outersurface of side wall 47 of the housing 21. The bracket 127 includes alower semi-cylindrical seat 128 for spring 125, and an upright back 127Adefining an aperture 127B. The upper end of spring 126 bears against thebottom of brush holder 119 and urges it radial away from the centralaxis of rotation. A shaft or pin 130 extends radially of the brushholder 119 and rotatably receives an adjusting lever 153 which is heldin place by a cap 151 having a flange 151A which include an aperture151B which receives the shaft 130 of the brush holder. The flange 151Aof cap 151 extends through the opening 125A of bracket 127. A cap screw154 is placed through an aperture in the flange 151A and aperture 127Bof bracket 127 to hold the adjusting assembly in place and maintain thespring 126 in compression for the entire adjustment range.

The brush holder 119 is assembled to the bracket 127 by having thebracket placed in the opening 125A of the rear extension 125 of thebrush holder. The extension 125 is shaped to receive and engage theedges of the seat 128. This permits the brush holder 119 to slide in aradial direction relative to the axis of rotation of the disc, butrestraining axial, circumferential or rotational motion of the brushholder. It also facilitates brush replacement. Turning to FIGS. 4A, 5Aand 15, the brush holder 119 is held in a predetermined radial positionagainst the bias of the spring 126 by means of adjusting lever 153 whichis rotatably received on pin 130 and includes a cam surface 135 (FIG. 5)which extends in a generally helical path about the axis of the pin 130.The outer limit position of the adjusting lever 153 is fixed by the cap151, which allows the lever 153 to rotate. Spring 126 exerts a radialoutward force against the brush holder 119 and lever 153. A pin 138 isfixed in the radial shaft 130 (FIG. 15) and extends beneath the cap 151.

As the handle 133 of lever 153 is rotated clockwise (looking radiallytoward the axis of rotation), the portion of cam surface 133 furthestfrom the axis of disc rotation engages the pin 138, thus enabling thespring to raise the brush holder and brushes to a raised position asseen in FIG. 16. As the lever 153 is rotated counterclockwise, pin 138engages the portion of cam surface 132 closest to the axis of rotation,thus lowering the brushes to the position of FIG. 15.

It will be appreciated that the brushes are guided into the reservoirside 23A of the disc 23 and retained in that position without straddlingthe edge of the disc due to the bevel 116 at the edge of the disc. Inother words, the beveled edge 116 insures that the bristles of thebrushes 120-122 will be on the reservoir side of the disc 23 for variouslevels of adjustment, as seen in FIG. 16, where the brushes are locatedsuch that their distal ends are adjacent the periphery of the disc, tothat of FIG. 15 wherein the brushes are more deeply set and the ends ofthe brushes are radially inward of the seed orifices.

Still referring to FIG. 15, on the left side of the disc 23 there areseed cells emerging from the seed reservoir, some of which have a singleseated seed, but others of which have duplicate seeds. As a seed cellbearing a duplicate, such as the cell generally designated 139 in FIG.15 encounters the first brush set 120, it can be seen that one of theseeds is dislodged and the other seed may be moved slightly from theseed orifice. The upper seed, however, is returned to the seed orificedue to the suction of the vacuum when the seed passes the brush set 120,captured by the radial recess of the cell. That is, during thismovement, the seed rests in the radial recess 139A of the seed cell 130.It has been found that the use of a single brush does not consistentlyand reliably eliminate all duplicates. A second brush (the two tufts areconsidered as one brush) downstream of the first, such as the onedesignated 121, removes further duplicates not corrected by the firstbrush, but again, the second brush set does not eliminate all of theduplicates as desired. It has been found that by using three brushes(with each brush along the direction of disc motion extending furtherinward) in sequence and as illustrated in FIG. 15, singulation isperformed reliably and repeatedly so that substantially all of the seedcells have one seed but not duplicates.

Turning now to FIGS. 3A and 17-19, the release of the seeds for deliveryto the furrow will now be discussed. Turning first to FIG. 17, the disc23 is rotating with the near side of the disc in a downward direction.The cross section of the vacuum cover in FIG. 17 is at an angle relativeto the end wall 75 as seen from FIG. 17A. It will be observed that priorto passing beneath the end wall 75 (see also FIG. 18), the seed cellsare carrying single seeds. The seed immediately adjacent the end wall 75is designated S in FIGS. 17 and 18. The interior of the vacuum chamber,85A extends right up to the interior surface 75A of the end wall 75,maintaining the seed S secured to the disc 23 by means of the vacuumbeing communicated to the seed through the seed orifice, as discussedabove.

However, as soon as the seed cell passes beneath the end wall 75 (seeseed position S1 in FIG. 18), the vacuum is removed from the vacuum side23B of the disc 23 as seen in FIG. 17. In other words, the seed cellpasses immediately into the open sector 78 defined as the angularposition between the start end wall 74 and the terminal end wall 75 ofthe vacuum chamber and adjacent (but radially outward of) thecontinuation 83 of the inner wall 82 of the vacuum housing. It will beobserved that both sides of the disc are fully exposed to the atmosphereonce a seed cell passes beneath the end wall 75, as further illustratedat 79 in FIGS. 3A and 19 and discussed above. As a result, the releaseof the seed is immediate because the retaining vacuum no longer retainsthe seed once it passes beyond terminating end wall 75.

The openings 54 and 55 in the seed housing and openings 52 in the discall cooperate to equalize the pressure within the seed reservoir. Thisproduces a more uniform differential pressure retaining individual seedson the disc and reduces or eliminates any “chimney” effect in thedischarge chute.

Moreover, as illustrated in FIG. 18, which is a view taken from thereservoir side 23A of the seed disc 23, once the seed cell passes to theatmosphere side of the terminating end wall 75 of the vacuum housing,the seed cell moves to the left as it continues rotating, but the seeditself, such as that designated S1 in FIG. 18 is free to fall. Moreover,it is unencumbered by any lateral wall or rise in the seed cell. Inother words, the seed is delivered freely and without obstructiontangentially outwardly of the rotating disc for an unencumbered andunobstructed delivery to the furrow, as illustrated at S2 in FIG. 18.

FIG. 20 shows a diametric cross section of the meter, illustrating thatthe radial cross sectional area of the vacuum chamber increases whenproceeding from the start wall 74 and the terminating wall 75 of thevacuum housing to the vacuum coupling 92.

FIG. 21 illustrates the structure of the vacuum cover 22 which sealsagainst the periphery of the opposing vacuum side of disc 23, and theengagement between side wall 47 of the seed housing 21 (which, togetherwith vacuum cover 22 forms a housing, divided by the disc into a seedreservoir and a vacuum chamber) and the peripheral edge of the disc 23.In FIG. 21, the vacuum is not applied. When vacuum is applied to thevacuum housing, the perimeter of the vacuum side of the disc engages theopposing edge of the vacuum cover to form a seal. Again, the seal is notan absolute seal, and allows some air to pass, but not in significantquantities.

Having thus disclosed in detail an illustrated embodiment of theinventions, persons skilled in the art will be able to modify certainaspects of the structure which has been disclosed and to substituteequivalent elements for those described while continuing to practice theprincipal of the invention; and it is, therefore, intended that all suchmodifications and substitutions be covered as they are embraced withinthe spirit and scope of the appended claims.

1. An air seed meter for an agricultural planter comprising: a housingdefining a seed reservoir for storing seed and a vacuum chamber; a discmounted in said housing for rotation about an axis and having aplurality of seed cells for seating and retaining seeds, said discmounted to separate said seed reservoir and said vacuum chamber andhaving a seed side and an opposing vacuum side; said vacuum chamberhaving a start wall and end wall and an outer wall, said outer wallextending circumferentially between said start wall and said end wall toenclose said vacuum side of said disc adjacent a plurality of said seedcells, said vacuum chamber defining a central opening exposing a centralportion of said vacuum side of said disc to the atmosphere, andcharacterized in that a center of said central opening is offsetrelative to the axis of rotation of said disc.
 2. The meter of claim 1wherein said outer wall of said vacuum cover includes an inner side wallhaving a generally circular inner rim contacting said disc.
 3. The meterof claim 2 wherein said inner rim of said vacuum cover includes aplurality of circumferential contact sections, adjacent contact sectionsseparated by a first groove extending between said central opening ofsaid vacuum cover and said vacuum chamber, and allowing atmospheric airto flow into said vacuum chamber to clear fines from said disc.
 4. Themeter of claim 1 characterized in that a region between said rim of saidinner side wall of said vacuum cover and said disc form acircumferential contact region having a radial width wider than a radialwidth of said contact region of said rim, whereby wear on said disc isspread out over an extended area greater than the area of saidcircumferential contact region of said rim, thereby reducing wear onsaid disc.
 5. The meter of claim 3 wherein each of said first groovesextending in a generally radial direction of said contact rim of saidvacuum cover has an increasing cross sectional area proceeding in adirection into said vacuum chamber, and wherein each of said firstgrooves is inclined in the direction of rotation of said disc proceedingalong the direction of air flow through said first grooves.
 6. The meterof claim 5 wherein each of said circumferential contact sectionsincludes at least three of said circumferential grooves.
 7. The meter ofclaim 4 wherein each circumferential contact section of said rim of saidinner side wall of said outer wall of said vacuum cover defines aplurality of grooves extending thereabout, adjacent grooves separated bya circumferential contact surface.
 8. The meter of claim 2 wherein saidrim of said inner side wall of said vacuum cover is beveled to assist inscraping debris from the adjacent surface of said disc within saidcentral opening of said vacuum cover.
 9. The meter of claim 1 whereinsaid start wall of said vacuum cover is inclined at a portion adjacentsaid disc to extend upwardly and away from said disc when proceeding inthe direction of rotation of said disc, said inclined portion contactingthe adjacent surface of said disc to remove debris.
 10. The meter ofclaim 1 wherein said vacuum cover defines an open sector extending aboutthe periphery of said disc between said end wall and said start wall,whereby said vacuum side of said disc is exposed to atmospheric pressureto release a seed secured to each seed cell as it passes beneath saidend wall of said vacuum cover.
 11. The meter of claim 10 whereininterior surfaces of said housing are roughened to reduce theaccumulation of particulate matter thereon.
 12. The meter of claim 1wherein said housing includes a seed housing attached to said vacuumcover, one of said seed housing and vacuum cover defining a firstperipheral rim having a plurality of mounting openings, the other ofsaid seed housing and vacuum cover defining a second peripheral rimcontacting said first peripheral rim and having a plurality of mountingmembers adapted to couple in releasable locking engagement with saidmounting openings when said vacuum cover is rotated in the direction ofdisc rotation relative said vacuum housing.
 13. The meter of claim 1wherein said disc defines a plurality of air inlet holes arranged aboutthe axis of rotation of said disc and located within said centralopening of said vacuum housing to permit atmospheric air to pass throughsaid disc into said seed reservoir.
 14. The meter of claim 13 whereinsaid housing includes a seed housing having a back wall and a generallycylindrical side wall, said back wall and said side wall of said seedhousing each defining an opening to admit atmospheric air into said seedreservoir.
 15. The meter of claim 14 further including an insert mountedto said seed housing to cover said opening in said back wall thereof andincluding a plurality of elongated air inlet slots to permit air to flowthere through.
 16. The meter of claim 1 wherein said vacuum housingincludes a vacuum coupling adapted to couple to a suction source, saidvacuum coupling located adjacent a mid-point of said vacuum coverapproximately equally spaced from said start wall and said end wall,said vacuum housing having a cross sectional area along a radial plane,which cross sectional area increases progressively from said start walland said second wall proceeding toward said vacuum coupling.
 17. An airseed meter for an agricultural planter comprising: a housing defining aseed reservoir, a discharge chute and a vacuum chamber; a disc mountedin said housing for rotation about an axis and having a plurality ofseed cells for seating and retaining seeds, said disc mounted to atleast partially define said seed reservoir and said vacuum chamber, saiddisc having a beveled outer edge on a seed reservoir side thereof, eachseed cell located adjacent said beveled edge and constructed to allowsaid seeds to release in a radially outward motion relative to said axisof rotation and into said discharge chute; and a singulator eliminatingseed doubles from said seed cells, said singulator including a brushholder securing at least three brushes spaced circumferentially aboutsaid disc, each brush extending inwardly of said beveled edge of saiddisc to locations adjacent said seed cells to engage seeds adjacent saidcells to dislodge duplicate seeds from each cell.
 18. The meter of claim17 further comprising an adjustment device including a rotary lever forlocating said brush holder at a desired radial position relative to saiddisc.
 19. The meter of claim 17 wherein said adjustment device includesa rotatable member defining a cam surface; a cam connected to said brushholder and engaging said cam surface, said cam surface extendingprogressively away from said axis of rotation of said disc; and a leverconnected to said rotatable member to adjust the radial position of saidbrush holder relative to said axis of rotation of said disc.
 20. Themeter of claim 19 characterized in that a distal end of each of saidbrushes is located progressively radially inwardly of said seed cellsproceeding in the direction of rotation of said disc.
 21. The meter ofclaim 17 further comprising: a drive shaft rotatably mounted to saidhousing and extending through said disc and outwardly of said centralopening of said vacuum cover for coupling to a planter drive externallyand laterally outboard of said meter.
 22. The meter of claim 21 furthercomprising a drive coupling connected to said drive shaft, said drivecoupling including a plurality of drive members elongated laterally andinclined relative to a radial line such that each drive member extendscloser to said axis of rotation of said disc proceeding in saiddirection of rotation of said disc; and wherein said disc defines aplurality of elongated openings sized and located to receive said drivemembers in driving engagement.